This document relates generally to minimally-invasive surgical systems, devices, and methods, and particularly, but not by way of limitation, to a system and method of minimally-invasive exovascular aneurysm treatment.
An aneurysm is an abnormal dilatation of a blood vessel. Brain aneurysms pose a particular risk of rupture and resulting hemorrhage, resulting in possible significant loss of brain function and even death. Autopsy studies have estimated that between about 1.5% and 8% of the population have intracranial aneurysms. Between 60,000 and 80,000 cerebral aneurysms are diagnosed annually in the U.S. Of these patients, about 20,000 to 30,000 are diagnosed following the occurrence of subarachnoid hemorrhage. The annual risk of an aneurysmal rupture is about 2%. Patients that experience aneurysmal rupture typically experience a mortality rate of about 50-60%. If the ruptured aneurysm is left untreated, about 25-35% of such patients will die of recurrent hemorrhage. For about 20-40% of those patients that do survive, the ruptured aneurysm results in a significant deficit in neurological function.
One conventional technique for treating a brain aneurysm uses standard open surgical intervention techniques. A craniotomy is performed to create a relatively large opening in the patient""s skull. The surgeon uses conventional surgical instruments to retract intervening brain tissue to expose the blood vessel at the aneurysm for direct visualization. With the aneurysm and associated blood vessel in view, the surgeon manipulates and treats the aneurysm using traditional surgical instruments to clip or staple either the body of the vessel or the neck of the aneurysm. Although such surgical clipping yields a high likelihood of procedural success, it is highly invasive. Therefore, it risks inducing associated brain trauma, thereby requiring a long recovery time. Moreover, a significant number of brain aneurysms are located very deep in the brain, rendering such conventional surgical techniques difficult.
Another technique for treating a brain aneurysm uses an endovascular approach. For example, a catheter may be introduced (e.g., near a subject""s groin) through a blood vessel and advanced to the aneurysm. In one technique, a detachable coil is introduced through the endovascular catheter and xe2x80x9cpackedxe2x80x9d into the interior of the aneurysm. This coil, which is usually constructed of stainless steel and/or platinum wire, is intended to interrupt the turbulent blood flow into the aneurysm. The resulting blood clots within the interior of the aneurysm. This reduces the risk of aneurysmal rupture. Another endovascular method of treating aneurysms uses a detachable balloon. The balloon is inflated with cyanoacrylates to occlude the interior of the aneurysm. Yet another endovascular method of treating aneurysms introduces an intravascular stent or graft that occludes the adjacent neck of an aneurysm sufficiently to interrupt blood flow into the aneurysm while maintaining continued flow through the native vessel.
These endovascular techniques for treating aneurysms, however, have not exhibited as high a likelihood of success as the open surgery techniques discussed above. Moreover, application of the endovascular techniques is generally limited to non-bifurcating, small-neck aneurysms, which actually constitute a small percentage of the clinically-diagnosed aneurysms. Furthermore, some aneurysms are exceedingly difficult to reach endovascularly because they require traversal of a long tortuous path through the accessing vessels. For these and other reasons, the present inventors have recognized a need for improved techniques and associated devices for accessing and treating brain or other aneurysms.
In contrast to the above-discussed open surgery and endovascular approaches to treating aneurysms, this document discusses a minimally-invasive exovascular approach to treating an aneurysm. Using such a minimally-invasive technique, the surgeon need only make a small opening for inserting an exovascular instrument to the aneurysm. In order to perform the treatment, the surgeon need not visualize the aneurysm directly. Instead, a magnetic resonance imaging (MRI), computed tomography (CT), or other suitable imaging device is provided to allow the surgeon to exovascularly guide a minimally-invasive aneurysm treatment device through the brain to the aneurysm, apply the treatment device to the desired portion of the aneurysm, and then remove the aneurysm treatment device. In a further example, an image-guided entry device is used to provide more accurate targeting and determination of a trajectory from the minimally-invasive entry opening to the aneurysm to be treated. The minimally-invasive techniques discussed in this document may permit more effective treatment of aneurysms that would be difficult to access or treat using endovascular techniques. Moreover, these minimally-invasive techniques may result in less shifting of brain tissue than open surgery techniques. This may permit more accurate targeting of the aneurysm, and less trauma to the intervening brain tissue.
In one example, this document discusses a system that includes an elongate exovascular probe. The probe includes proximal and distal ends. The probe also includes an outer dimension that is less than about 18 millimeters to permit the probe to be introduced through a similarly-sized minimally-invasive opening in a portion of a subject""s skull and exovascularly advanced to an aneurysm within the skull. The system also includes an aneurysm treatment device carried by the probe. The aneurysm treatment device is dimensioned to permit the aneurysm treatment device to be introduced through the opening.
In another example, this document discusses a method of aneurysm treatment. The method includes forming an opening in a subject""s skull. The opening having a diameter that is less than or equal to the diameter of a burr hole. A probe is exovascularly inserted through the opening to an aneurysm using real-time or preoperative imaging to guide the probe to the aneurysm. An aneurysm treatment device is exovascularly introduced through a lumen in the probe to the aneurysm. Using the aneurysm treatment device, a morphology of the aneurysm is altered. Other aspects of the invention will be apparent on reading the following detailed description of the invention and viewing the drawings that form a part thereof.